Enamine is a general term for αβ-unsaturated amines, which are extremely useful compounds in the field of synthetic organic chemistry. Enamines are generally synthesized by a dehydrative condensation reaction between an aldehyde or ketone and a secondary amine. In the synthesis of enamines, the dehydrative condensation reaction has been well known to proceed more smoothly when one equivalent of an aldehyde or ketone is reacted with more than one equivalent of a secondary amine than when one equivalent of an aldehyde or ketone is reacted with one equivalent of a secondary amine. Accordingly, when the excess amount of the secondary amine is used in said synthetic reaction, the desired product, the enamine, and the secondary amine are included in the final product obtained after the reaction is completed. Enamines thus obtained can be used for other reactions without any purifications, but in some reactions, for example, such as a condensation reaction between an enamine and a halogenated alkyl compound, purification of the enamine is necessary because the secondary amine inhibits the reaction. As a procedure for the purification of enamines, fractional distillation is generally known, but especially in the production of a large amount of enamine, large scale fractional distillation equipment is required, and additionally, this purification procedure is generally accompanied by disadvantages such as the decomposition of the enamines in the course of the fractional distillation at a high temperature. Furthermore, it is known that enamines generally have poor stability against water [Barton S. D.; Ollis W. D. Comprehensive Organic Chemistry; Sutherland I. O. Ed.; Pergamon: New York, 1979; Vol. 2, Part 6], and studies on the rate (mechanism) of hydrolysis of various enamines have been reported [J. Org. Chem., 32, 1111 (1967); J. Org. Chem., vol. 40, No. 5, 607-614 (1975); J. Am. Chem. Soc., 82, 4261-4270 (1970), etc.].